Mechanical refrigeration systems, and related heat transfer devices such as heat pumps and air conditioners, using refrigerant liquids are well known in the art for industrial, commercial and domestic uses. Chlorofluorocarbons (CFCs) were developed in the 1930s as refrigerants for such systems. However, since the 1980s the effect of CFCs on the stratospheric ozone layer has become the focus of much attention. In 1987 a number of government signed the Montreal Protocol to protect the global environment setting forth a timetable for phasing out the CFC products. Subsequent amendments to this protocol accelerated the phase-out of these CFCs and also scheduled the phase-out of HCFCs. Thus, there is a requirement for a non-flammable, non-toxic alternative to replace these CFCs and HCFCs. In response to such demand industry has developed a number of hydrofluorocarbons (HFCs), which have a zero ozone depletion potential.
Hydrofluorcarbons such as difluoromethane (HFC-32), 1,1,1-trifluoroethane (HFC-143a) and 1,1-difluoroethane (HFC-152a) have essentially no ozone depletion potential (ODP) and therefore, they have been found to be acceptable refrigerants and, in some cases, as potential blowing agents in the production of plastic foams.
1,1,1-Trifluoroethane (HFC-143a) is a component of the commercially available non-ozone depleting refrigerant blend 507A (a.k.a. AZ-50). One of the commercial processes for making HFC-143a is by reacting 1,1,1-trichloroethane (HCC-140a) with HF directly. HCC-140a was once one of the most highly produced chemicals in the world. It was once used as a solvent and more recently as a raw material for making 1,1-dichloro-1-fluoroethane (HCFC-141b). With the phase out of CFC's and HCFC's as stipulated by the Montreal Protocol, the production of HCC-140a has decreased dramatically. By the “rules” of supply and demand the price has increased dramatically. Similarly, most uses of HCFC-141b are being legislated away; the economic impact of this can result in relatively high cost for this as a feedstock, since other uses are prohibited. Thus, there is a need for an alternate method for the manufacture of HFC-143a that can use, in part or all, alternate organic starting materials and combinations there of.
U.S. Pat. No. 2,478,932, Miller et al., Allied Chemical & Dye relates to gas-phase reactions for the fluorination of 1,1,1-dichlorofluoroethane using an aluminum fluoride or complex basic aluminum fluoride catalyst. Such gas phase reaction are not really desirable because they must operate at higher temperatures, generally create more byproducts, have lower volumetric throughput, and have short catalyst life.
U.S. Pat. No. 4,766,258, Komatsu et al., Asahi Kasei, relates to liquid phase production of HFC-143a from individual hydrochlorocarbons using a tin-based catalyst.
U.S. Pat. No. 4,968,850, Franklin et al., Solvay & Cie, relates to liquid phase production of HFC-143a from unsaturated chlorocarbons, such as vinylidene chloride, using tin-based catalyst and an organophosphorus inhibitor. The amount of HFC-143a produced is very little, i.e., 2% or less.
U.S. Pat. No. 5,574,191, Balthasart et al., Solvay & Cie, relates to co-production of HFC-143a with vinylidene fluoride and at least one of 1-chloro-1,1-difluoroethane (HCFC-142b) and 1,1-dichloro-1-fluoroethane (HCFC-141b) in liquid phase without use of a catalyst. The process example in this patent produced only 6.1% HFC-143a.
U.S. Pat. No. 5,770,779, Nappa, et al., E.I. duPont de Nemours and Company, relates to production of HFC-143a using tin-based catalyst and at least one compound selected from metal and nonmetal alkoxides
U.S. Pat. No. 6,080,899, Bradley, et al., AlliedSignal Inc., relates to operating conditions for producing compounds such as HFC-143a including a solvent not taking part in the reaction.
U.S. Pat. No. 6,339,178, Lantz, et al., Atofina, relates to production of HFC-143a from HFCF-142b alone in the presence of a fluorination catalyst.
U.S. Pat. No. 6,630,610, Swain, et al., AlliedSignal Inc., relates to operating conditions for producing HFC-143a from 1,1,1-trichloroethane (HCC-140a).
WO 96/05156, Swain, AlliedSignal Inc., relates to production of HFC-143a from HCC-140a alone in the absence of a solvent.
JP 8-217704 relates to co-production of HFC-143a with HFC-32, using HCC-140a as the feed for the HFC-143a.
Korean Patent 2000027318, Na, et al., describes preparing HFC-143a in liquid phase using antimony catalyst from a mixture of HCFC-141b and HCFC-142b.
Korean Patent 184381 describes co-production of HFC-143a and HCFC-142b in the liquid phase without catalyst.
Russian Patent 2 160 245, Orlov, et al., describes co-production of HFC-143a, HCFC-142b, and HCFC-141b from HCC-140a or vinylidene chloride in liquid phase.
Chinese Patents 1106779 and 1044802 relate to production of HFC-143a from 1-chloro-1,1-difluoroethane (HCFC-142b) in liquid phase using antimony-based catalyst.
In view of the rapidly rising cost of 1,1,1-trichloroethane there is a need for an alternative process that enables one to produce HFC-143a with different reactant(s), which can change depending upon fluctuations in the prices of these reactant raw materials.